Apparatus for heat exchange between a gas and fine-grained material

ABSTRACT

APPARATUS FOR EFFECTING A HEAT EXCHANGE BETWEEN A GAS AND FINE-GRAINED MATERIAL. THE APPARATUS IS COMPRISED OF A NUMBER OF PROCESSING CHAMBERS ARRANGED ONE ON TOP OF THE OTHER AND HAVING OPENINGS BETWEEN THEM WHICH PROVIDE COMMUNICATION BETWEEN SUCCESSIVE CHAMBERS. THE APPARATUS ALSO INCLUDES AT LEAST ONE MATERIAL INLET ARRANGED TO INSERT MATERIAL IN THE UPPERMOST CHAMBER AND AT LEAST ONE GAS OUTLET TUBE FORMING AN OPENING AT THE TOP OF THE UPPERMOST CHAMBER. ACCORDING TO THE PRESENT INVENTION, A BAFFLE PLATE IS ATTACHED TO THE EDGE OF THE OPENING AT THE TOP OF EACH OF THE PROCESSING CHAMBERS TO PROJECT INWARD INTO THE ASSOCIATED CHAMBER AND GUIDE THE FLOW OF MATERIAL AND GAS.

June 1, 1971 w. DERCKS ETAL 3,581,405

APPARATUS FOR HEAT EXCHANGE BETWEEN A GAS AND FINE'GRAINED MATERIAL Filed D80. 5, 1968 2 Sheets-Sheet 1 Inventors: ner JDercks willielm ilghanhmnebusch Meg June 1, '1971 w DERCKS ETAL 3,581,405

- E APPARATUS FOR HEAT EXCHANGE BETWEEN A GAS AND FINE-GRAINED MATERIAL Filed Dec. 5,, 1968 2 Sheets-Sheet 8 F/G.5 Fl

T" "T 4 i 4 Inventors.-

Werner D-ercks Wilhelm Hohenhinnebusch Patented June I, 1971 3,581,405 APPARATUS FOR HEAT EXCHANGE BETWEEN A GAS AND FINE-GRAINED MATERIAL Werner Dercks and Wilhelm Hohenhinnebusch, Essen,

Germany, assignors to Fried. Krupp Gesellschaft mit beschrankter Haftung, Essen, Germany Filed Dec. 3, 1968, Ser. No. 780,703 Claims priority, application Germany, Dec. 5, 1967, P 16 01 125.9 Int. Cl. F26b 17/14 US. Cl. 34-57 5 Claims ABSTRACT OF THE DISCLOSURE Apparatus for effecting a heat exchange between a gas and fine-grained material. The apparatus is comprised of a number of processing chambers arranged one on top of the other and having openings between them which provide communication between successive chambers. The apparatus also includes at least one material inlet arranged to insert material in the uppermost chamber and at least one gas outlet tube forming an opening at the top of the uppermost chamber. According to the present invention, a baffle plate is attached to the edge of the opening at the top of each of the processing chambers to project inward into the associated chamber and guide the flow of material and gas.

BACKGROUND OF THE INVENTION The present invention relates to apparatus for effecting a heat exchange between a gas and fine-grained material. The apparatus is comprised of a number of processing chambers arranged one on top of the other and having openings between them which provide communication between successive chambers. The apparatus also includes at least one material inlet arranged to insert material in the uppermost chamber and at least one gas outlet tube forming an opening at the top of the uppermost chamber.

The apparatus operates to pass the fine-grained material from the uppermost to the lowermost and to pass the gas from the lowermost to the uppermost one of the chambers. The material thus falls downward against the flow of the gas, the speed of fall of the individual material particle being slower than the speed of flow of the gas. This arrangement allows the greatest possible amount of the heat contained in the gas to be transferred to a material.

In apparatus of the type described above which is known in the art the speed of the gaseous stream must be kept low to make it possible for the material particles to move downward against the stream. Although apparatus of the type described above with a plurality of unidirectional-flow heat exchangers connected in series can be provided with cyclones to separate the material from the gas, these cyclones produce a large drop in the gas pressure. In addition, they provide a considerable increase in the cost of the apparatus.

SUMMARY OF THE INVENTION An object of the present invention, therefore, is to provide apparatus for the exchange of heat between a gas and fine-grained material, which apparatus does not exhibit the disadvantages of the prior art described above.

This object, as well as other objects which will become apparent in the discussion that follows, is achieved, according to the present invention, by providing a baffle plate in each of the processing chambers which is attached to and projects inward from the processing chamber immediately above, or, in the case of uppermost processing chamber, the lower end of the gas outlet tube. The introduction of these baffle plates cause a rotational flow about a horizontal axis in each of the individual processing chambers, which flow increases the separation or dissociation of the material from the stream of gas. In addition, flow dead spaces are formed in the processing chambers causing whirling of the fine-grained material that is entrained with the outgoing stream of gas.

In a particular embodiment of the present invention the bafiie plates are constructed as tubes which extend around the entire circumference of the openings between the chambers. In the case of the uppermost chamber the gas outlet tube forms the baffle plate by extending into the uppermost chamber. The batfie plate (or, rather, baffie tube) axes form an angle with the axis of the chambers so that the material will be guided or bunched into a narrow stream before it enters the next lower chamber.

The apparatus, according to the present invention, can be employed to preheat and simultaneously deacidize limestone, raw cement powder, dolomite or the like having a grain size up to 3 mm. in diameter if the openings and the baffle plates are constructed to extend in a straight line across the entire horizontal cross section of the chambers. In many cases it is sufficient if only the upper opening of the lowermost chamber, and the baffle plate extending downward therefrom into the lowermost chamber, extend across the entire crosssection of the apparatus.

It is practical if a shoulder is provided below the material inlet line so that the material supplied to the apparatus will impinge against it. If the surface against which the material is directed is substantially perpendicular to the direction of flow of the material, the material will be caused to fan out and be distributed in the stream of gas in the uppermost chamber.

Particularly when the apparatus is employed to heat extremely fine-grained material, it is practical to limit the amount of dust removed with the gas from the uppermost chamber. Thus, according to a particular feature of the present invention, the apparatus is provided with at least one centrifugal separator, connected at the upper end of the gas outlet tube, with a material return line leading back to the uppermost chamber.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view through a portion of heat exchange apparatus according to a first preferred embodiment of the present invention.

FIG. 2 is a partly cross-sectional view through a portion of heat exchange apparatus according to a second preferred embodiment of the present invention.

FIG. 3 is a cross-sectional view through a portion of heat exchange apparatus according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along the line 44 through the apparatus of FIG. 3.

FIG. 5 is a partly cross-sectional view through a portion of heat exchange apparatus having centrifugal separators according to a fourth preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, FIG. 1 shows heat exchange apparatus comprising a series of substantially cylindrical processing chambers 1 interconnected by circular openings 2 situated coaxially with the axis of the chambers. The upper and lower ends of the processing chambers 1 are conically shaped. A material inlet line 3 projects into the uppermost processing chamber 1; this inlet directs the material against the upper surface 6 of a shoulder which likewise protrudes inside the chamber. The surface 6 is arranged approximately perpendicular to the direction with which the material is discharged from the inlet and therefore causes the material to fan out and be distributed within the gas stream in the chamber 1. The uppermost chamber is also provided with a gas outlet tube 4 which, like the openings 2, is arranged coaxially with the axis of the chambers 1.

In accordance with the present invention a baffle plate 7 is arranged to project inside of each processing chamber 1 from the lower end of the processing chamber immediately above or, in the case of the uppermost chamber, from the lower end of the gas outlet tube 4.

The heat exhcange apparatus illustrated in FIG. 2 has a plurality of processing chambers 1 arranged one above the other and interconnected through openings 2. In this embodiment the baffle plates projecting into the processing chambers 1 are constructed as tubes 8 which extend around the entire circumference of the openings 2. The axis 9 of the tubes 8 form an angle a with the axis 10 of the heat exchange apparatus. As shown in the figure, the opening at the bottoms of the tubes 8 can form any arbitrary angle with their axes 9.

The magnitude of the angle a should be sufficient to cause the material which falls downward through the openings 2 to be collected into a narrow stream. The magnitude of a thereof depends on the size of the openings and the length of their associated baflle plates; in a typical case, where the length of the baflle plates is approximately equal to the diameter of the openings, or may lie in the range of to 50; in a typical embodiment of a heat exchange apparatus according to the present invention, or is about 23 The embodiment of the heat exchange apparatus illustrated in FIGS. 3 and 4 is especially suitable for deacidizing limestone, raw cement powder, dolomite, and the like. As can best be seen in FIG. 4, the openings 11 have one straight edge which extends nearly all the way across the circular cross section of the chambers 1. The baffle plate 12 is a flat plate, in this embodiment, attached to the lower end of each chamber along the above-mentioned straight edge of the opening 11. The openings in this embodiment of the heat exchange apparatus are staggered in such a way as to cause the falling material and the rising gas to move first to one side, and then to the other, of the apparatus.

The baffle plate in the uppermost processing chamber 1 is formed by the gas outlet tube 4 which projects vertically into the chamber. The material inlet line 3 is arranged in the uppermost chamber to drop the fine-grained material against the slanted lower wall of the chamber.

The apparatus, in the embodiment illustrated in FIG. 5, is provided with centrifugal separators at the upper end of the gas outlet tube 4. The gas which rises in the outlet tube is directed into the top of two individual cylindrical separators 13 tangentially to their cylindrical surfaces. The separators have cone-shaped lower portions that terminate in material return lines 14 which feed the material back into the uppermost processing chamber 1. The gas is removed from the cylindrical separators via outlet pipes which project vertically from the tops of the separators.

In the embodiment of FIG. 5, the material inlet line 3 may project directly into the gas outlet tube 4 since any material which is forced upward through the gas outlet tube will be trapped in the separators.

The material fed into the apparatus according to the invention slides along the walls of the processing chambers as well as the baffle plates arranged at the point between the chambers. The material is thus directed into the cross current of the upwardly flowing stream of gas, causing a fine distribution of the material in the gas. Because of the rotational flow which is caused by the baflie plates, the material will be separated from the gas to a great extent at the wall opposite the material inlet 3. The material will then slide downwards over the baflle plate between the uppermost and the next uppermost processing chambers. The process will then be repeated in a similar manner in the next uppermost chamber, and so on. As a result, the gas will exchange nearly all of its heat energy with the falling material without causing the material to flow with it out of the outlet tube.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations.

We claim:

1. In apparatus for exchanging heat between an upwardly flowing gas and a downwardly flowing fine-grained material, comprising a plurality of processing chambers connected one on top of the other along a common axis and defining openings therebetween providing a single path of communication between said chambers, at least one material inlet arranged to insert material into the uppermost one of said chambers and at least one gas outlet tube forming an opening at the top of said uppermost chamber, said openings being means for permitting the material to flow downwardly from the uppermost to the lowermost of said chambers and the gas to flow upwardly from the lowermost to the uppermost of said chambers, the improvement comprising a tube attached to the edge of a respective one of each of said openings and arranged around the entire circumference thereof, the axis of said each tube forming an angle with the axis of said chambers which is suflicient to cause the material to be collected into a narrow stream.

2. The improvement defined in claim 1, wherein the one of said tubes in said uppermost chamber is attached to said gas outlet tube.

3. The improvement defined in claim 2, wherein said each of said tubes is disposed at an angle relative to that surface of the chamber therebelow onto which the material falls.

4. The improvement defined in claim 3, further comprising a shoulder arranged in said uppermost chamber beneath said material inlet, said shoulder having a surface facing said material inlet that is substantially perpendicular to the inflow direction of said material.

5. The improvement defined in claim 3, further comprising at least one centrifugal separator connected to the upper end of said gas outlet tube, said centrifugal separator having a material return line means for returning the material separated therein to said uppermost chamber.

References Cited UNITED STATES PATENTS 2,613,138 10/1952 Van Loon 34-57X 2,866,625 12/1958 Sylvest 34171X 2,886,899 5/1951 Watkins 34-57 3,010,806 11/1961 Berry 34-171X 3,049,343 8/1962 Helming 34171X 3,092,471 6/ 196 3 Stromeyer 34-171X ALBERT W. DAVIS, JR., Primary Examiner US. Cl. X.R. 34171, 178, 228 

